Thin film transistor (TFT) panels are frequently fabricated on very thin substrates such as 0.7 mm thick glass panels. The back faces of the TFT panels, i.e. the sides opposite the front faces carrying the TFTs, are subsequently laminated onto glass support plates, commonly using a UV-curable resin, so that subsequent process steps can be performed without damaging or distorting the fragile TFT panels. This approach is well known in the art and is described in U.S. Pat. No. 5,827,757 issued Oct. 27, 1998 to Robinson, et al., which is hereby incorporated by reference. During this process, solid objects should not make contact with the front face of the TFT panel because burrs or dust particles found on solid objects can crush films on the TFT panel.
A previous approach for laminating a TFT panel onto a glass support plate involves holding the TFT panel using a vacuum chuck with a piece of lint-free paper forming a cushion between the chuck and the front face of the TFT panel to avoid having the metal chuck make direct contact with the front face of the TFT panel. Lint-free paper can be used as a cushion because it is both porous and cushioning. Panel laminated according to this approach are offered commercially in this country by the assignee hereof, and further information therein is available at its website, HOLOGIC.COM.
Artifacts can sometimes be found on images captured using TFT panels that have been manufactured using lint-free paper. These artifacts are a result of uneven curing of UV resin used in the TFT panels due to reflection of UV light from the lint-free free paper to the TFT panels. Lint-free paper can also leave small paper particle on the TFT panel that must subsequently be removed using a spin cleaning process. Spin cleaning can add cost and complexity to the TFT panel manufacturing process and can occasionally promote crazing of the TFT panel thereby lowering the manufacturing yield. The vacuum chuck used in this process does not shield the TFT panel from potentially harmful vapors that emanate from the UV-curable resin used to laminate the TFT panel to the glass support plate.